Hard x-ray photoemission spectroscopy of Bi2S3 thin films

The electronic structure of polycrystalline Bi2S3 thin films deposited by thermal evaporation under high vacuum conditions was investigated with respect to their potential use as absorber materials in p-i-n solar cells by means of hard x-ray photoemission spectroscopy at the PETRA III synchrotron. A clear influence of the post-deposition treatment on the electronic structure could be observed, resulting in a lowering of the Fermi level as well as in a change of the electronic states in the valence band. Furthermore, chemical shifts of Bi2S3 were determined in the bulk-sensitive hard x-ray regime as ΔEB,Bi=1.35 eV and ΔEB,S=−2.80 eV.